The subject matter described herein generally relates to radio frequency (RF) interference cancellation. Specifically, the embodiments herein relating to real-time RF interference cancellation.
A two-way RF communication system is one in which signals are transmitted bi-directionally between transceivers. Each transceiver may include a transmitter to transmit signals and a receiver to receive incoming transmissions. To avoid interference between the transmitted signal and the received signal, the communication system may receive and transmit signals at different times in what is called half-duplex communication. However, half-duplex techniques may not allow efficient two-way communication because transmitting time is lost while signals are being received.
Full-duplex techniques allow signals to be transmitted and received simultaneously, providing increased bandwidth relative to half-duplex techniques. To avoid interference between the transmitted and received signals, full-duplex techniques may employ various strategies to separate these signals from one another. For example, full-duplex communication may employ time-division multiplexing (TDM), frequency-division multiplexing (FDM), or code-division multiplexing (CDM). In TDM, the transmitted and received signals may be transferred in different timeslots, but at a fast enough rate that the transferring appears to be simultaneous. In FDM, the transmitted and received signals may be separated enough in frequency that their modulated spectra do not overlap, and each receiver may be tuned such that it will receive the intended frequency and reject its own transmitted signal. In CDM, the signals may carry certain codes that allow certain signals to be separated from other signals.
There are various techniques for RF interference cancellation that may be employed in a particular system. For example, certain duplex communication architectures may employ hardware RF cancellers. Often, the hardware RF canceller may not provide adequate canceling, and these systems may also use an additional canceller at baseband. Accordingly, such hardware-based canceling systems may be complex and may involve multiple cancellation filters. Other architectures may employ full-band cancellers that may cancel transmission components over the entire Nyquist bandwidth. However, such cancellers may not operate in real-time, due to the extensive computational requirements.